Eliza



w (No Model.)

B. P. CLARK.

' ELECTRIC MOTOR.

No. 359,429. Patented Mar. 15, 1887.

INVENTOR M $4M,

WITNESSES ATTORNEY UNITED STATES PATENT OFFICE.

ERNEST PAUL CLARK, OF NEW YORK, N. Y., ASSIGNOR OF PART TO ANN ELIZAAPPLEGATE AND JAMES H.

SEYMOUR, BOTH OF SAME PLACE.

ELECTRIC MOTOR.

SPECIFICATION forming part of Letters Patent No. 359,429, dated March15,1887.

Application filed November 23, 1886. Serial No. 219,703.

To all whom it may concern.-

Be it known that I, ERNEST PAUL CLARK, a citizen of the United States,residing; in the city, county, and State of New York, have inventedcertain new and useful Improvements in Electric Motors; and I do herebydeclare that the following is a full, clear, and exact description ofthe invention, such as will enable others skilled in the art to which itappertains to make and use the same.

My invention is concerned with providing means for increasing theefficiency of that class of devices known as electric motors. It hasbeen found in practice that rotary electric motors are more eff cientwhen the pole-pieces of the armature pass in the closest possibleproximity to the field-magnet poles, while the efliciency ofdynamo-electric machines is not increased by such proximity. Forexample, taking the ring-armature as a type, it has been found that asmooth ring-armature like that of Gramme is the better form for adynamo-electric generator, whereas the toothed ring-armature ofPacinotti is more effective for use in motors.

Now, in Letters Patent of the United States No. 330,005, granted to meon the 10th of November, 1885, I have shown and described adynamo-electric machine in which I cause an armature of the Gramme typeto rotate be tween internal and external field-magnet polepieces.My-present invention ris mainly di-- rected to making this machine anefficient motor. To this end I employ, in place of the Gramme ring, aPacinotti ring with some alterations, and I find .that the results fullywarrant the change of form. The ring of Pacinnotti was provided withexternal teeth or projections, between which the wire was wound.I'provide my ring with internal and external teeth or projections, thoseon the inside being narrowed so as to admit of the proper winding of thering. I find that I secure far better results in this way than with aring having the externalprojectionsalone.

In the accompanying drawings, which illustrate my invention and form apart of this specification, Figure l is a side elevation of the motorembodying my invention. Fig. 2 is a detail of the ring or core uponwhich the armature-coils are wound, showing also a section through theinner magnet pole-pieces; and Fig. 3 illustrates the form of myfield-magnet cores and pole-pieces.

(No model.)

Referring to the drawings by letter, A and B are uprights or standardson which my motor is supported. On these standards, respectively, aremounted the magnets O and D, forming the field-magnets of my motor. Thecores of the two upper helices of the said magnets are preferably formedin one casting, as are also those of the two lower helices of therespective magnets. The form of the castings is shown in Fig. 3, byreference to which it will be seen that each casting is so shaped as topresent a pole-piece both within and without the rotating armature. Theouter polepieces I have designated by the letter E, and the innerpole-pieces by the letter F. The armature G of my motor is mounted on ashaft, H, supported by the standards A and B. The armature-core is madein the form of a ring of iron having external teeth or projections, G,and internal teeth or projections, G". The armature is wound in theusual manner be tween the said teeth. By reference to Fig. 2 it will beseen that I re-enforce the inner polepieces by a magnet, I, whosehelices stand at 'internal and external pole-pieces, I find that I bringthe armature very effectually under the influence of .my field-magnetsand secure a motor of high efficiency.

The operation of my motor is the same as that of other machines of itsclass, and I have therefore not described it in detail.

lVhat I claim is- In an electric motor, the combination, with a pair offield-magnets provided with external and internal pole-pieces, and athird magnet whose cores are joined to the said inner polepieces, of aring-armature having external and internal projections, as and for thepurpose set forth. s

In witness whereof I have hereunto affixed my name in the presence oftwo subscribing witnesses.

ERNEST PAUL CL ARK.

IVitnesses:

GEORGE H. STOOKBRIDGE, Onas. H. SAAL.

